Zwitterionic Copolymer‐Supported Ionogel Electrolytes: Impacts of Varying the Zwitterionic Group and Ionic Liquid Identities

Abstract

A series of copolymer scaffolds containing zwitterionic (ZI) functional groups, synthesized in situ in two alkylimidazolium cation-based ionic liquids, has been created by using two different ZI monomers to yield nonvolatile ionogel electrolytes that exhibit high ionic conductivities and a wide range of elastic moduli. Although all of the examined ionogel formulations consist of 80 mol % ionic liquid, gel properties are observed to depend both on zwitterion content within the copolymer scaffold, as well as the specific ionic liquid/zwitterion pairing. Low zwitterion contents (ca. 1 mol %) generate a notable increase in ionogel room-temperature ionic conductivity com-pared to that of their non-ZI ionogel analogues, whereas higher zwitterion contents (up to 18.5 mol %) yield stiff gels containing a large density of ZI noncovalent cross-links. This highlights the dual functionality of the ZI groups within zwitterion-containing copolymer-supported ionogel electrolytes. All the ionogels synthesized in this study exhibit room-temperature ionic conductivity values in the range of 3-12 mS cm À 1 with compressive elastic modulus values varying between approximately 1-1000 kPa, suggesting their suitability for the design of safer flexible electrochemical devices, including wearable sensors or supercapacitors.

Understanding Electric Field‐Dependent Structure Variation of Functional Ionic Liquids at the Electrode Interface

“…A deep understanding of the structure of the electrode-liquid interface is a vital basis for applications in electrochemical engineering, for example, electrochemical reaction, [1] energy storage, [2][3][4] gas separation, [5] supercapacitor, [6][7][8] sensor devices, [2,[9][10] and so on. During the practical electrochemical process, ionic liquids (ILs) have been widely used as the new solvent or electrolyte due to their extremely low volatility, high thermal stability and wide chemical window.…”

Overview of Ionogels in Flexible Electronics

“…Rebollar et al [149] polymerize the zwitterionic (ZI) monomers of sulfobetaine vinylimidazole (SBVI) and 2-methacryloyloxyethyl phosphorylcholine (MPC) in two kinds of ILs [C 1 C 2 Im][TFSI] and [C 1 C 2 Im][TCB] to prepare ionogel, respectively (Figure 8a). The ionogel exhibits excellent mechanical properties by the dipole-dipole interaction between the amphoteric polymers.…”

“…(b) The conductivities of ZI ionogels with different zwitterion contents. Adapted with permission from Ref [149]…”

Design of highly stretchable deep eutectic solvent‐based ionic gel electrolyte with high ionic conductivity by the addition of zwitterion ion dissociators for flexible supercapacitor

“…For instance, Panzer group reported zwitterionic copolymer ionogels which exhibit ionic conductivity up to 6.7 mS cm −1 and compressive elastic moduli up to 11 MPa. [ 31‐34 ] Our previous work also demonstrated that zwitterionic polymer could help increasing the mechanical strength and ionic conductivity of polyelectrolyte hydrogels. [ 35 ]…”